Energy-angle spectra of secondary neutrons from 27Al(p,nX) and 208Pb(p,nX) reactions for space-shielding applications

Neutron contribution is an important component of the secondary radiation field. For energies up to 400 MeV encompassing most of the incident spectrum for trapped protons and solar-energetic particle events, energy-angle spectra of secondary neutrons produced from the proton-induced neutron-production reaction are evaluated using the optical model for the direct reactions, the Hauser-Feshbach model for the equilibrium emission, and the exciton model for the pre-equilibrium emission, based on selected reference measurements. As a result, a good agreement has been achieved for the entire emission-energy and angle range, except for slight discrepancies at pre-equilibrium emission energies.